Rotary vacuum pumps



Jan. 21, 1969 H. ELGRINDROD ETAL I 3,423,014

ROTARY VACUUM PUMPS Filed Feb. 6, 1967 Sheet of 2 Harold E. Gmndrul J lm A SmH k INVENTORS 1969 H. E. GRINDROD ETAL 3,423,014

ROTARY VACUUM PUMPS Filed Feb. 6, 1967 Sheet g fg I 10 s a a :1: *zuE 5g H E rmJroA J Smdk mvsmons United States Patent 9 Claims ABSTRACT OF THE DISCLOSURE A rotary vacuum pump provided with an oil reservoir, a pump chamber and a duct between the reservoir and the chamber whereby the reservoir supplies oil to the chamber for both lubrication and sealing. Valve means at the end of the duct in the reservoir biased closed. A member mounted on a pump shaft and adapted to be driven by the pump and a further member in closely axially spaced relationship from the first member and freely rotatable relative to the shaft, the second member having an engaging means adjacent its periphery, a bore from said reservoir to said chamber, a plunger in the bore which has one end in contact with the engaging means and the other end in contact with the valve means whereby it is urged open when the pump is operative.

This invention concerns a rotary vacuum pump of the kind (hereinafter termed of the kind referred to) including an oil reservoir adapted to supply oil to the pump chamber for the dual purposes of lubrication and sealing, there being an oil duct between said reservoir and pump chamber for this purpose.

It is an object of the present invention to provide means to close the oil supply duct to the pump chamber when the rotary pump ceases to operate thereby preventing the pump chamber from filling with oil and preventing oil from being sucked back into the system being evacuated.

According to the present invention a rotary vacuum pump of the kind referred to is characterised by the provision of valve means which normally operates to close the connection between said oil reservoir and said oil duct, but which may be opened to establish such connection, and means adapted to sense operation of the rotary vacuum pump and to open said valve means in response thereto.

The invention will be further apparent from the following description with reference to the figures of the accompanying drawings, which show, by way of example only, one form of rotary vacuum pump embodying the invention.

Of the drawings:

FIG. 1 shows a view of the pump sectioned on the axis thereof; and

FIG. 2 shows a transverse cross-section through the pump on the line IIII of FIG. 1.

Referring firstly to FIG. 1, it will be seen that the pump includes an oil reservoir 10 located above the pump chamber which is generally indicated at 11. The construction and operation of the rotary pump itself which may be of any suitable kind will not be described in detail since such is not important to an understanding of the present invention. It will suffice to say that the pump shaft 12 is extended from the pump chamber 11 through an end wall thereof to protrude into a cylindrical chamber 13 defined between such wall and a cup-shaped member 14 sealably secured thereto. Two discs 15 and 16 are secured in axially spaced relationship on the protruding end of the shaft 12 and are separated by a collar 17 of ice predetermined axial length likewise secured to the shaft 12. A further disc 18 is provided on the shaft 12 between the discs 15 and 16 but this disc 18 is freely rotatable on the collar 17. Carefully predetermined small clearances exist between the disc 18 and the discs 15 and 16 lying to either side thereof, such clearances being determined by the axial length of the collar 17 and thickness of the disc 18. The chamber 13 is filled with oil, and an oil seal 19 surrounds the shaft 12 to prevent the migration of the oil to the pump chamber 11.

Referring now to FIG. 2 it will be seen that a duct 20 communicates with the base of the oil reservoir 10. This duct 20 is adapted to supply oil from the reservoir 10 to the pump chamber 11 in known manner. A circular valve seat 21 surrounds the duct 20 at its upper end within the reservoir 10. A floating bar 22 is provided over the seat 21 and carries a rubber seal 23 secured to its underside. The bar 22 is urged downwardly by compression springs 24 mounted on studs 25 so that the seal 23 is loaded against the seat 21 thereby cutting off the supply of oil to the pump chamber 11.

A bore 26 extends from the reservoir 10 to the chamber 13 and locates a plunger 27 whose upper end bears against the underside of the bar 22 and whose lower end is located in a notch 28 provided on the periphery of the disc 18.

In use when the pump is operative with the shaft 12 rotating, the discs 15 and 16 are rotated and the resulting oil drag on the disc 18 causes the latter to move in the direction of the arrow A (see FIG. 2) thereby lifting the plunger 27 and hence bar 22 against the action of the springs 24 and opening the valve constituted by the parts 21 and 23 allowing feed of oil to the pump chamber 11.

Immediately the pump ceases to operate the oil drag is removed from the disc 18 which returns to its initial position thereby allowing the valve to close all under the action of the springs 24 thus preventing the chamber 11 from filling with oil and the danger of oil being sucked back into the system which was being evacuated.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as, might readily occur to one skilled in the art, being possible without departing from the scope thereof, as defined by the appended claims.

What is claimed is:

1. In a rotary vacuum pump including an oil reservoir, a pump chamber and duct between said reservoir and said chamber, whereby said reservoir is adapted to supply oil to said chamber for both lubrication and sealing, the improvement which comprise-s valve means at the end of said duct in said reservoir biased closed, a first member mounted on a pump shaft and adapted to be driven with and by said rotary vacuum pump, a second member disposed in closely axially spaced relationship from said first member and freely rotatable relative to said shaft, and a fluid medium surrounding said members, said second member having an engaging means adjacent its periphery, a bore from said reservoir to said chamber, a plunger in said bore and having one end in contact with said engaging means, the other end of said plunger in contact with said valve means, whereby said means is urged open when said pump is operative.

2. A rotary vacuum pump according to claim 1 wherein said first member comprises two discs disposed in coaxial spaced relationship, said shaft being rotatable with the vacuum pump, said second member comprising a third disc disposed between said first-mentioned two discs.

3. A rotary vacuum pump according to claim 2 wherein said engaging means is a notch, whereby rotation of said first member causes angular movement of said third disc and axial movement of said plunger in said bore to open said valve means.

4. A rotary vacuum pump according to claim 3 wherein said plunger slides in said bore, to open said valve means.

5. A rotary vacuum pump according to claim 4 wherein said valve means comprises a circular valve seat surrounding the end of said oil duct in the oil reservoir, a floating bar having a valve seal adapted to engage said valve seat, and spring means adapted to urge said bar to hold said seal against said seat, said plunger being adapted to lift said bar against the action of said spring means to open the valve when the vacuum pump is operative.

6. A rotary vacuum pump according to claim 2 wherein said discs are disposed within a chamber which is filled with said fluid medium.

7. A rotary vacuum pump according to claim 6 wherein said fluid medium comprises oil.

8. A rotary vacuum pump according to claim 3 wherein said valve means comprises a circular valve seat surrounding said end of said duct, a floating bar having a valve seal thereon adapted to engage said valve seat, and spring means adapted to urge said bar to hold said seal against said seat, said plunger being adapted to lift said bar against the action of said spring means to open the valve when the vacuum pump is operative.

9. A rotary vacuum pump according to claim 4 wherein said valve means comprises a circular valve seat surrounding the end of said duct, a floating bar having a valve seal thereon adapted to engage said valve seat, and spring means adapted to urge said bar to hold said seal against said seat, said plunger being adapted to lift said bar against the action of said spring means to open the valve when the vacuum pump is operative.

References Cited UNITED STATES PATENTS 2,070,151 2/1937 Westin 230-205 3,053,439 9/1962 Brill 230-205 3,265,295 8/1966 Cyr 23O207 R. M. WALKER, Primary Examiner. 

